remove all reference to master.sh etc from docs and code

[nhsavage]

note co-pilot flagged some useful doc changes needed when reviewing #163 - deal with these soon

• This error message still references running master.sh, but this script now combines hindcast+forecast and is intended to replace the older scripts. Updating the message to describe the actual prerequisite (hindcast products/terciles exist for the same settings) will make failures easier to diagnose.
  scripts/run_all.sh:16
• This PR deletes scripts/master.forecast.sh, but there are still user-facing references to that script elsewhere (e.g. docs and error messages). This will mislead users and can complicate troubleshooting. Please update those references to point to the new workflow/script name.

[nhsavage]

if about to update to use a python script + driver yml could combine these changes with doc chagnes for that

[nhsavage]

note this will probably be covered when #173 is merged